The History of Furniture Springs

Furniture suspensions throughout the centuries

And specifically the last century and a half

In this article, we will extensively discuss the development of furniture suspensions in chronological order. Some suspensions will be discussed in detail, while others will be mentioned but also have their own in-depth article in this knowledge base, to which we will link.

The origin of various suspensions

Throughout the centuries, furniture makers and upholsterers have extensively experimented with ways to create more comfort in their seating furniture. This started with solid wooden seats, then seats made of stretched leather, to various types of upholstery on wooden seats, from leather to textile and fur. Experimentation also involved the frames to achieve more seating comfort, such as creating rocking chairs or working with different types of wood to utilize different properties.

Subsequently, various fillings were used under those upholsteries, from animal hair (such as horsehair), clothing scraps, cotton wadding, blue wadding (recycled clothing), crin végétal (a processing of dwarf palm leaf to replace expensive horsehair), to rubber foams in the mid-last century, and synthetic fillings such as fiberfill and polyethers and polyether cold foams. But also for the basis of seating comfort, much thought was given: the internal suspensions.

Although the emphasis in previous centuries was mainly on the external styles of furniture, and developments in the internal structure progressed slowly, a significant change occurred at the beginning of the last century. New suspensions were rapidly devised, which both improved seating comfort and increased production speed. From the reconstruction after the Second World War, a growing demand for furniture also had to be met quickly. Although developments are certainly not standing still, the 20th century can certainly be called the golden age for the internal workings of seating furniture. And we will further discuss the developments of suspensions in this article.

Fig. 1. Coil spring 5x36 (5 turns high, 3.6mm wire thickness), copper-plated steel

The Coil Spring

The first suspensions in seating furniture were made with double-conical springs, or coil springs. These springs were sewn onto a base of woven jute webbing, and at the top, the springs were "linked" together with rope, both to adjust their height and to keep them at a fixed distance from each other.

As you can see above, the springs are first sewn onto a jute webbing mat (Fig. 2a). Then they are linked together with rope (Fig. 2b). In this more unique case of the furniture shown, the springs are left high when linking, and to keep them in place, they are first tied along the top edge of the spring unit with a steel wire (or edge wire). This happens before linking. After linking, a tightly woven jute fabric is stretched over the springs, and the whole is covered with traditionally natural fillings such as horsehair, crin végétal (crin, literally "vegetable horsehair"). This entire assembly is sewn into place and in turn covered with a (cotton) wadding layer. Now the upholstery can go over it. This whole is called 'deep upholstery' in technical jargon.

You understand, this is a rather labor-intensive job. And as with all labor-intensive tasks, the industry has constantly been looking for faster methods of (furniture) construction, preferably while maintaining quality.

Ready-made suspensions

To drastically reduce the labor-intensity of furniture upholstery, ready-made spring units were produced, held together with iron wire and/or band iron. These were called spring interiors.

This allowed the final upholsterer to simply place the springs, secure them to the frame with staples, and set them with only a handful of ropes. In this way, many more pieces of furniture could be produced in the same amount of time, while maintaining the quality of the suspension. The only difference the interior made compared to loose springs is that loose springs provide a silent seat. In the interior, the springs are held together by weaving them through each other (clearly visible in Fig. 3b). This creates a characteristic soft rustling sound from the seat when it is used.

And development did not stand still. Such spring interiors are of course nice for larger sofas and smoking chairs, but what about dining chairs?

No problem at all: interiors were also produced for the size of chairs, albeit based on the old-fashioned coil spring (Fig. 4a). Because these springs were closed, they could no longer be woven through each other, so the springs were connected with a spiral among themselves, and steel wire or band iron on the outside. Preferably, the interior was made round in shape to fit in almost any model of chair frame.

In addition, spring garnitures, also called patent springs, were also produced (Fig. 4b). Here, single-conical springs were woven together at the bottom with band iron, and held together at the top with an edge wire. They are held together with spring clips among themselves. The advantage of this type of spring is that it sinks relatively low into the frame, allowing the seat to maintain its flat upholstery.

Deep upholstery? Flat upholstery?

You may have already gathered from the text, but deep upholstery is upholstery with a reasonably high raised edge, made from springs with a natural filling top layer, which have been shaped using professional sewing stitches. This therefore does not include modern foam upholstery, regardless of the height of the front.

Flat upholstery is actually the collective term for all other upholsteries where the fillings are not sewn. Whether it's a chair seat that is only filled with crin and wadding, horsehair and wadding, or foam upholstery, they all fall under it.

Modern flat upholstery

While classic flat upholstery mainly consisted of jute webbing (Fig. 5a) with a layer of filling between jute fabric, the rise of foams (natural foam rubber > synthetic foam rubber > foam plastics > contemporary polyurethane foams such as polyether and polyether cold foam) brought many more possibilities for flat upholsteries in modern, sleek design styles. However, even though the foams themselves already had sufficient springiness, it was not enough for quality requirements to simply continue processing them on a jute webbing mat. So, development continued on suspensions that were as flat as possible.

Webbing as suspension

The first route of further development was based on webbing. The stiff, non-stretchable jute webbing already existed, but with the rise of rubber, experimentation (reasonably successful) was done on a springy webbing, by developing a rubber band with an open-weave canvas core as reinforcement (Fig. 5b). A major problem with rubber is its limited lifespan when used in open air (the underside of the seat) and warm environments at room temperature. The rubber then dries out relatively quickly, causing the webbing to harden and easily crack. It is still available, but at a premium price compared to alternatives. An excellent alternative is the later developed elastic webbing (Fig. 5c). Here too, rubber is used, but the rubber is now used as a stretchable core in a polyester thread, from which the webbing is woven. This relatively well protects the rubber against environmental influences, and this webbing lasts much longer than its all-rubber predecessor.

A more in-depth article about webbing can be found here

Flatter steel springs

Fig.6. The long tension spring

The second route of further development was in the field of steel springs. For example, armchairs were produced in which long tension springs (Fig. 6) were stretched across the width of the seat (and sometimes also the back). Loose (foam) cushions could be placed on top of these, creating the first reasonably flat, sleek cushion upholsteries. To protect the cushion fabric, the tension springs were first covered with a cotton sleeve, or a heavy cotton fabric was stretched over the entire assembly.

The Spiralette

The next development became even flatter: the spiralette, as shown in Figs. 7a and 7b. In essence, this resembles a tension spring, but stretched out and flattened. Unlike the tension spring, these springs were stretched in the depth direction of the sofa, allowing larger furniture such as sofas to be developed in new sleek and linear models with this suspension. A development that paved the way for modern sleek design and countless other possibilities. But just like the tension spring, this spring is also not very common anymore. Development did not stand still. The next development was the spring as we know it now:

Fig. 8. The Nosag spring

The Nosag spring, also known as wave spring or zigzag spring

Properties of the nosag spring

Unlike the spiralette, the arches of the nosag spring move back and forth in a wavy motion. The spring is made of spring steel, and to create different stiffnesses, they are made in different wire thicknesses: 2.8mm, 3.0mm, 3.2mm, 3.4mm, 3.6mm, 3.8mm, and 4.0mm. The thicker the spring, the heavier the spring. Springs with thinner wire thicknesses (2.8 to 3.4mm) are extremely suitable for back suspensions, which have nothing to bear but only need to provide counterpressure. Springs of 3.6mm and thicker are ideal for seats, where the full upper body must be supported by the spring. In this case, the deeper the seat, the thicker the spring.

A frame in which nosag springs are incorporated must be provided with a sturdy framework that cannot be disrupted by the tension of the springs. Generally, two most common solutions are used for the seat frame:
- a framework of heavy beech slats, reinforced with an extra support slat or support partition per seat division
- or a framework of steel tubes, also with a support slat per seat division

Whether the furniture otherwise has a chipboard frame or a heavy beech frame, these are the minimum requirements for the framework of a nosag suspension. In contemporary new furniture, nosag springs are rarely used for the back anymore; elastic webbing is usually sufficient here. For the seat, they are used all the more, and by far the most commonly used wire thickness is 3.8mm. This is because the load-bearing capacity can also be regulated by adjusting the spacing of the springs, instead of choosing a different thickness of spring.

For a detailed article on nosag springs, including how to replace them, you can go here

Fig.9 Pocket springs for seating furniture

Pocket springs, the economical foam replacement

Pocket springs are relatively small, narrow springs made of thin spring wire. Their load-bearing capacity is therefore not derived so much from their steel thickness, but rather from the quantity used within a surface area. To prevent the springs from touching and tangling, each spring is enclosed in a fabric pocket. These pockets are then attached side by side to a top and bottom layer, creating a pocket spring mattress.

At the end of the last century, they were already used in the mattress industry. But as foam prices rose from the beginning of this century (with every oil price increase, the price went up and still does, while the price barely changed or not at all during a decline), especially for quality foams, other solutions were also sought in the seating furniture industry. Add to that the fact that the number of furniture stores and chains has increased enormously since the successes of the first Home Malls at the end of the last century. It would not be surprising, for example, if there are now more seating furniture items in stores than there are homes to place them in. And then you arrive at a final result where price fighters take every opportunity to push down the price of their seating furniture.

Since foam prices are volume prices, pocket springs come in ideally here. Roughly speaking: the volume of pocket springs consists of a few iron wires in a non-woven fleece fabric and air. By using pocket springs, larger cushions could and can be made, where sometimes 60 to 70% of the volume now consists of air, and still provides reasonable seating comfort. This has transformed the pocket spring from a luxury mattress spring to an ideal spring for the mass consumption market.